* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-02 4:51 [PATCH] virtio-net: fix qemu set used ring flag even vhost started Yajun Wu
@ 2024-04-02 6:53 ` Michael S. Tsirkin
2024-04-02 12:11 ` Philippe Mathieu-Daudé
2024-04-03 5:10 ` Michael Tokarev
2 siblings, 0 replies; 7+ messages in thread
From: Michael S. Tsirkin @ 2024-04-02 6:53 UTC (permalink / raw)
To: Yajun Wu; +Cc: qemu-devel, jasowang, maxime.coquelin, Jiri Pirko
On Tue, Apr 02, 2024 at 12:51:09PM +0800, Yajun Wu wrote:
> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
> should not touch used ring.
>
> But with vhost-user socket reconnect scenario, in a very rare case (has
> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
> following code path:
>
> #0 virtio_queue_split_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:511
> #1 0x0000559d6dbf033b in virtio_queue_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:576
> #2 0x0000559d6dbbbdbc in virtio_net_handle_tx_bh (vdev=0x559d703a6aa0, vq=0x7ff5f4c920a8) at ../hw/net/virtio-net.c:2801
> #3 0x0000559d6dbf4791 in virtio_queue_notify_vq (vq=0x7ff5f4c920a8) at ../hw/virtio/virtio.c:2248
> #4 0x0000559d6dbf79da in virtio_queue_host_notifier_read (n=0x7ff5f4c9211c) at ../hw/virtio/virtio.c:3525
> #5 0x0000559d6d9a5814 in virtio_bus_cleanup_host_notifier (bus=0x559d703a6a20, n=1) at ../hw/virtio/virtio-bus.c:321
> #6 0x0000559d6dbf83c9 in virtio_device_stop_ioeventfd_impl (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3774
> #7 0x0000559d6d9a55c8 in virtio_bus_stop_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:259
> #8 0x0000559d6d9a53e8 in virtio_bus_grab_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:199
> #9 0x0000559d6dbf841c in virtio_device_grab_ioeventfd (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3783
> #10 0x0000559d6d9bde18 in vhost_dev_enable_notifiers (hdev=0x559d707edd70, vdev=0x559d703a6aa0) at ../hw/virtio/vhost.c:1592
> #11 0x0000559d6d89a0b8 in vhost_net_start_one (net=0x559d707edd70, dev=0x559d703a6aa0) at ../hw/net/vhost_net.c:266
> #12 0x0000559d6d89a6df in vhost_net_start (dev=0x559d703a6aa0, ncs=0x559d7048d890, data_queue_pairs=31, cvq=0) at ../hw/net/vhost_net.c:412
> #13 0x0000559d6dbb5b89 in virtio_net_vhost_status (n=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:311
> #14 0x0000559d6dbb5e34 in virtio_net_set_status (vdev=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:392
> #15 0x0000559d6dbb60d8 in virtio_net_set_link_status (nc=0x559d7048d890) at ../hw/net/virtio-net.c:455
> #16 0x0000559d6da64863 in qmp_set_link (name=0x559d6f0b83d0 "hostnet1", up=true, errp=0x7ffdd76569f0) at ../net/net.c:1459
> #17 0x0000559d6da7226e in net_vhost_user_event (opaque=0x559d6f0b83d0, event=CHR_EVENT_OPENED) at ../net/vhost-user.c:301
> #18 0x0000559d6ddc7f63 in chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:62
> #19 0x0000559d6ddc7fdc in qemu_chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:82
>
> This issue causes guest kernel stop kicking device and traffic stop.
>
> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
> VRING_USED_F_NO_NOTIFY set.
>
> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> hw/net/virtio-net.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index a6ff000cd9..8035e01fdf 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -2865,6 +2865,10 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>
> + if (n->vhost_started) {
> + return;
> + }
> +
> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
> virtio_net_drop_tx_queue_data(vdev, vq);
> return;
> --
> 2.27.0
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-02 4:51 [PATCH] virtio-net: fix qemu set used ring flag even vhost started Yajun Wu
2024-04-02 6:53 ` Michael S. Tsirkin
@ 2024-04-02 12:11 ` Philippe Mathieu-Daudé
2024-04-02 12:41 ` Yajun Wu
2024-04-03 5:10 ` Michael Tokarev
2 siblings, 1 reply; 7+ messages in thread
From: Philippe Mathieu-Daudé @ 2024-04-02 12:11 UTC (permalink / raw)
To: Yajun Wu, qemu-devel, mst, jasowang, maxime.coquelin; +Cc: Jiri Pirko
Hi Yajun,
On 2/4/24 06:51, Yajun Wu wrote:
> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
"QEMU"
> should not touch used ring.
>
> But with vhost-user socket reconnect scenario, in a very rare case (has
> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
"QEMU"
> following code path:
>
> #0 virtio_queue_split_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:511
> #1 0x0000559d6dbf033b in virtio_queue_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:576
> #2 0x0000559d6dbbbdbc in virtio_net_handle_tx_bh (vdev=0x559d703a6aa0, vq=0x7ff5f4c920a8) at ../hw/net/virtio-net.c:2801
> #3 0x0000559d6dbf4791 in virtio_queue_notify_vq (vq=0x7ff5f4c920a8) at ../hw/virtio/virtio.c:2248
> #4 0x0000559d6dbf79da in virtio_queue_host_notifier_read (n=0x7ff5f4c9211c) at ../hw/virtio/virtio.c:3525
> #5 0x0000559d6d9a5814 in virtio_bus_cleanup_host_notifier (bus=0x559d703a6a20, n=1) at ../hw/virtio/virtio-bus.c:321
> #6 0x0000559d6dbf83c9 in virtio_device_stop_ioeventfd_impl (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3774
> #7 0x0000559d6d9a55c8 in virtio_bus_stop_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:259
> #8 0x0000559d6d9a53e8 in virtio_bus_grab_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:199
> #9 0x0000559d6dbf841c in virtio_device_grab_ioeventfd (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3783
> #10 0x0000559d6d9bde18 in vhost_dev_enable_notifiers (hdev=0x559d707edd70, vdev=0x559d703a6aa0) at ../hw/virtio/vhost.c:1592
> #11 0x0000559d6d89a0b8 in vhost_net_start_one (net=0x559d707edd70, dev=0x559d703a6aa0) at ../hw/net/vhost_net.c:266
> #12 0x0000559d6d89a6df in vhost_net_start (dev=0x559d703a6aa0, ncs=0x559d7048d890, data_queue_pairs=31, cvq=0) at ../hw/net/vhost_net.c:412
> #13 0x0000559d6dbb5b89 in virtio_net_vhost_status (n=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:311
> #14 0x0000559d6dbb5e34 in virtio_net_set_status (vdev=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:392
> #15 0x0000559d6dbb60d8 in virtio_net_set_link_status (nc=0x559d7048d890) at ../hw/net/virtio-net.c:455
> #16 0x0000559d6da64863 in qmp_set_link (name=0x559d6f0b83d0 "hostnet1", up=true, errp=0x7ffdd76569f0) at ../net/net.c:1459
> #17 0x0000559d6da7226e in net_vhost_user_event (opaque=0x559d6f0b83d0, event=CHR_EVENT_OPENED) at ../net/vhost-user.c:301
> #18 0x0000559d6ddc7f63 in chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:62
> #19 0x0000559d6ddc7fdc in qemu_chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:82
>
> This issue causes guest kernel stop kicking device and traffic stop.
>
> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
> VRING_USED_F_NO_NOTIFY set.
>
> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> ---
> hw/net/virtio-net.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index a6ff000cd9..8035e01fdf 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -2865,6 +2865,10 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>
> + if (n->vhost_started) {
Since you mentioned "in a very rare case", maybe use unlikely()?
> + return;
> + }
> +
> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
> virtio_net_drop_tx_queue_data(vdev, vq);
> return;
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-02 12:11 ` Philippe Mathieu-Daudé
@ 2024-04-02 12:41 ` Yajun Wu
2024-04-02 14:12 ` Philippe Mathieu-Daudé
0 siblings, 1 reply; 7+ messages in thread
From: Yajun Wu @ 2024-04-02 12:41 UTC (permalink / raw)
To: Philippe Mathieu-Daudé, qemu-devel@nongnu.org,
mst@redhat.com, jasowang@redhat.com, maxime.coquelin@redhat.com
Cc: Jiri Pirko
On 4/2/2024 8:11 PM, Philippe Mathieu-Daudé wrote:
> External email: Use caution opening links or attachments
>
>
> Hi Yajun,
>
> On 2/4/24 06:51, Yajun Wu wrote:
>> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
> "QEMU"
Ack.
>> should not touch used ring.
>>
>> But with vhost-user socket reconnect scenario, in a very rare case (has
>> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
> "QEMU"
Ack.
>> following code path:
>>
>> #0 virtio_queue_split_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:511
>> #1 0x0000559d6dbf033b in virtio_queue_set_notification (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:576
>> #2 0x0000559d6dbbbdbc in virtio_net_handle_tx_bh (vdev=0x559d703a6aa0, vq=0x7ff5f4c920a8) at ../hw/net/virtio-net.c:2801
>> #3 0x0000559d6dbf4791 in virtio_queue_notify_vq (vq=0x7ff5f4c920a8) at ../hw/virtio/virtio.c:2248
>> #4 0x0000559d6dbf79da in virtio_queue_host_notifier_read (n=0x7ff5f4c9211c) at ../hw/virtio/virtio.c:3525
>> #5 0x0000559d6d9a5814 in virtio_bus_cleanup_host_notifier (bus=0x559d703a6a20, n=1) at ../hw/virtio/virtio-bus.c:321
>> #6 0x0000559d6dbf83c9 in virtio_device_stop_ioeventfd_impl (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3774
>> #7 0x0000559d6d9a55c8 in virtio_bus_stop_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:259
>> #8 0x0000559d6d9a53e8 in virtio_bus_grab_ioeventfd (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:199
>> #9 0x0000559d6dbf841c in virtio_device_grab_ioeventfd (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3783
>> #10 0x0000559d6d9bde18 in vhost_dev_enable_notifiers (hdev=0x559d707edd70, vdev=0x559d703a6aa0) at ../hw/virtio/vhost.c:1592
>> #11 0x0000559d6d89a0b8 in vhost_net_start_one (net=0x559d707edd70, dev=0x559d703a6aa0) at ../hw/net/vhost_net.c:266
>> #12 0x0000559d6d89a6df in vhost_net_start (dev=0x559d703a6aa0, ncs=0x559d7048d890, data_queue_pairs=31, cvq=0) at ../hw/net/vhost_net.c:412
>> #13 0x0000559d6dbb5b89 in virtio_net_vhost_status (n=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:311
>> #14 0x0000559d6dbb5e34 in virtio_net_set_status (vdev=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:392
>> #15 0x0000559d6dbb60d8 in virtio_net_set_link_status (nc=0x559d7048d890) at ../hw/net/virtio-net.c:455
>> #16 0x0000559d6da64863 in qmp_set_link (name=0x559d6f0b83d0 "hostnet1", up=true, errp=0x7ffdd76569f0) at ../net/net.c:1459
>> #17 0x0000559d6da7226e in net_vhost_user_event (opaque=0x559d6f0b83d0, event=CHR_EVENT_OPENED) at ../net/vhost-user.c:301
>> #18 0x0000559d6ddc7f63 in chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:62
>> #19 0x0000559d6ddc7fdc in qemu_chr_be_event (s=0x559d6f2ffea0, event=CHR_EVENT_OPENED) at ../chardev/char.c:82
>>
>> This issue causes guest kernel stop kicking device and traffic stop.
>>
>> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
>> VRING_USED_F_NO_NOTIFY set.
>>
>> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
>> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
>> ---
>> hw/net/virtio-net.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index a6ff000cd9..8035e01fdf 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -2865,6 +2865,10 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
>> VirtIONet *n = VIRTIO_NET(vdev);
>> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>>
>> + if (n->vhost_started) {
> Since you mentioned "in a very rare case", maybe use unlikely()?
Ack.
>
>> + return;
>> + }
>> +
>> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
>> virtio_net_drop_tx_queue_data(vdev, vq);
>> return;
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-02 12:41 ` Yajun Wu
@ 2024-04-02 14:12 ` Philippe Mathieu-Daudé
0 siblings, 0 replies; 7+ messages in thread
From: Philippe Mathieu-Daudé @ 2024-04-02 14:12 UTC (permalink / raw)
To: Yajun Wu, qemu-devel@nongnu.org, mst@redhat.com,
jasowang@redhat.com, maxime.coquelin@redhat.com
Cc: Jiri Pirko
On 2/4/24 14:41, Yajun Wu wrote:
>
> On 4/2/2024 8:11 PM, Philippe Mathieu-Daudé wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> Hi Yajun,
>>
>> On 2/4/24 06:51, Yajun Wu wrote:
>>> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
>> "QEMU"
> Ack.
>>> should not touch used ring.
>>>
>>> But with vhost-user socket reconnect scenario, in a very rare case (has
>>> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
>> "QEMU"
> Ack.
>>> following code path:
>>>
>>> #0 virtio_queue_split_set_notification (vq=0x7ff5f4c920a8,
>>> enable=0) at ../hw/virtio/virtio.c:511
>>> #1 0x0000559d6dbf033b in virtio_queue_set_notification
>>> (vq=0x7ff5f4c920a8, enable=0) at ../hw/virtio/virtio.c:576
>>> #2 0x0000559d6dbbbdbc in virtio_net_handle_tx_bh
>>> (vdev=0x559d703a6aa0, vq=0x7ff5f4c920a8) at ../hw/net/virtio-net.c:2801
>>> #3 0x0000559d6dbf4791 in virtio_queue_notify_vq
>>> (vq=0x7ff5f4c920a8) at ../hw/virtio/virtio.c:2248
>>> #4 0x0000559d6dbf79da in virtio_queue_host_notifier_read
>>> (n=0x7ff5f4c9211c) at ../hw/virtio/virtio.c:3525
>>> #5 0x0000559d6d9a5814 in virtio_bus_cleanup_host_notifier
>>> (bus=0x559d703a6a20, n=1) at ../hw/virtio/virtio-bus.c:321
>>> #6 0x0000559d6dbf83c9 in virtio_device_stop_ioeventfd_impl
>>> (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3774
>>> #7 0x0000559d6d9a55c8 in virtio_bus_stop_ioeventfd
>>> (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:259
>>> #8 0x0000559d6d9a53e8 in virtio_bus_grab_ioeventfd
>>> (bus=0x559d703a6a20) at ../hw/virtio/virtio-bus.c:199
>>> #9 0x0000559d6dbf841c in virtio_device_grab_ioeventfd
>>> (vdev=0x559d703a6aa0) at ../hw/virtio/virtio.c:3783
>>> #10 0x0000559d6d9bde18 in vhost_dev_enable_notifiers
>>> (hdev=0x559d707edd70, vdev=0x559d703a6aa0) at ../hw/virtio/vhost.c:1592
>>> #11 0x0000559d6d89a0b8 in vhost_net_start_one
>>> (net=0x559d707edd70, dev=0x559d703a6aa0) at ../hw/net/vhost_net.c:266
>>> #12 0x0000559d6d89a6df in vhost_net_start (dev=0x559d703a6aa0,
>>> ncs=0x559d7048d890, data_queue_pairs=31, cvq=0) at
>>> ../hw/net/vhost_net.c:412
>>> #13 0x0000559d6dbb5b89 in virtio_net_vhost_status
>>> (n=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:311
>>> #14 0x0000559d6dbb5e34 in virtio_net_set_status
>>> (vdev=0x559d703a6aa0, status=15 '\017') at ../hw/net/virtio-net.c:392
>>> #15 0x0000559d6dbb60d8 in virtio_net_set_link_status
>>> (nc=0x559d7048d890) at ../hw/net/virtio-net.c:455
>>> #16 0x0000559d6da64863 in qmp_set_link (name=0x559d6f0b83d0
>>> "hostnet1", up=true, errp=0x7ffdd76569f0) at ../net/net.c:1459
>>> #17 0x0000559d6da7226e in net_vhost_user_event
>>> (opaque=0x559d6f0b83d0, event=CHR_EVENT_OPENED) at
>>> ../net/vhost-user.c:301
>>> #18 0x0000559d6ddc7f63 in chr_be_event (s=0x559d6f2ffea0,
>>> event=CHR_EVENT_OPENED) at ../chardev/char.c:62
>>> #19 0x0000559d6ddc7fdc in qemu_chr_be_event (s=0x559d6f2ffea0,
>>> event=CHR_EVENT_OPENED) at ../chardev/char.c:82
>>>
>>> This issue causes guest kernel stop kicking device and traffic stop.
>>>
>>> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
>>> VRING_USED_F_NO_NOTIFY set.
>>>
>>> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
>>> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
>>> ---
>>> hw/net/virtio-net.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>>> index a6ff000cd9..8035e01fdf 100644
>>> --- a/hw/net/virtio-net.c
>>> +++ b/hw/net/virtio-net.c
>>> @@ -2865,6 +2865,10 @@ static void
>>> virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
>>> VirtIONet *n = VIRTIO_NET(vdev);
>>> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>>>
>>> + if (n->vhost_started) {
>> Since you mentioned "in a very rare case", maybe use unlikely()?
> Ack.
Thanks, queued squashing:
- if (n->vhost_started) {
+ if (unlikely(n->vhost_started)) {
return;
}
>>
>>> + return;
>>> + }
>>> +
>>> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
>>> virtio_net_drop_tx_queue_data(vdev, vq);
>>> return;
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-02 4:51 [PATCH] virtio-net: fix qemu set used ring flag even vhost started Yajun Wu
2024-04-02 6:53 ` Michael S. Tsirkin
2024-04-02 12:11 ` Philippe Mathieu-Daudé
@ 2024-04-03 5:10 ` Michael Tokarev
2024-04-03 5:21 ` Yajun Wu
2 siblings, 1 reply; 7+ messages in thread
From: Michael Tokarev @ 2024-04-03 5:10 UTC (permalink / raw)
To: Yajun Wu, qemu-devel, mst, jasowang, maxime.coquelin
Cc: Jiri Pirko, qemu-stable
02.04.2024 07:51, Yajun Wu:
> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
> should not touch used ring.
>
> But with vhost-user socket reconnect scenario, in a very rare case (has
> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
> following code path:
...
> This issue causes guest kernel stop kicking device and traffic stop.
>
> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
> VRING_USED_F_NO_NOTIFY set.
This seems to be qemu-stable material, even if the case when the issue
happens is "very rare", -- is it not?
Thanks,
/mjt
> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> ---
> hw/net/virtio-net.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index a6ff000cd9..8035e01fdf 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -2865,6 +2865,10 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>
> + if (n->vhost_started) {
> + return;
> + }
> +
> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
> virtio_net_drop_tx_queue_data(vdev, vq);
> return;
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] virtio-net: fix qemu set used ring flag even vhost started
2024-04-03 5:10 ` Michael Tokarev
@ 2024-04-03 5:21 ` Yajun Wu
0 siblings, 0 replies; 7+ messages in thread
From: Yajun Wu @ 2024-04-03 5:21 UTC (permalink / raw)
To: Michael Tokarev, qemu-devel@nongnu.org, mst@redhat.com,
jasowang@redhat.com, maxime.coquelin@redhat.com
Cc: Jiri Pirko, qemu-stable
On 4/3/2024 1:10 PM, Michael Tokarev wrote:
> External email: Use caution opening links or attachments
>
>
> 02.04.2024 07:51, Yajun Wu:
>> When vhost-user or vhost-kernel is handling virtio net datapath, qemu
>> should not touch used ring.
>>
>> But with vhost-user socket reconnect scenario, in a very rare case (has
>> pending kick event). VRING_USED_F_NO_NOTIFY is set by qemu in
>> following code path:
> ...
>> This issue causes guest kernel stop kicking device and traffic stop.
>>
>> Add vhost_started check in virtio_net_handle_tx_bh to fix this wrong
>> VRING_USED_F_NO_NOTIFY set.
> This seems to be qemu-stable material, even if the case when the issue
> happens is "very rare", -- is it not?
If you mean this fix needs back port to previous version? Yes.
> Thanks,
>
> /mjt
>
>> Signed-off-by: Yajun Wu <yajunw@nvidia.com>
>> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
>> ---
>> hw/net/virtio-net.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index a6ff000cd9..8035e01fdf 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -2865,6 +2865,10 @@ static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
>> VirtIONet *n = VIRTIO_NET(vdev);
>> VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
>>
>> + if (n->vhost_started) {
>> + return;
>> + }
>> +
>> if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
>> virtio_net_drop_tx_queue_data(vdev, vq);
>> return;
^ permalink raw reply [flat|nested] 7+ messages in thread